1. Volume 89, Issue 5, Pages 765-771 (May 1997)
Cbfa1, a Candidate Gene for Cleidocranial Dysplasia Syndrome, Is Essential for Osteoblast Differentiation and Bone Development 
Florian Otto, Anders P Thornell, Tessa Crompton, Angela Denzel, Kimberly C Gilmour, Ian R Rosewell, Gordon W.H Stamp, Rosa S.P Beddington, Stefan Mundlos, Bjorn R Olsen, Paul B Selby, Michael J Owen 
Cell 
Volume 89, Issue 5, Pages (May 1997)
DOI: /S (00)

2. Figure 1 Generation of Cbfa1 Mutant Mice by Gene Targeting
(a) Schematic diagram of the Cbfa1 locus, the targeting vector, and the targeted allele. Restriction enzyme sites are indicated (B, BglII; E, EcoRI; N, NotI; S, SacI; X, XhoI). The closed box corresponds to the exon containing the Q/A repeat domain of the Cbfa1 gene.
(b) Southern blot analysis showing correct 5′ targeting of the Cbfa1 locus. Genomic DNA samples were prepared from tails of homozygous (−/−), heterozygous (+/−), and wild-type (+/+) mice and were digested with EcoRI and probed as indicated (probe A). The resulting 10 and 7.3 kb bands correspond to the wild-type and mutated genotypes, respectively.
(c) Southern blot analysis showing correct 3′ targeting of the Cbfa1 locus. Genomic DNA from wild-type (+/+) or heterozygous (+/−) mice were digested with XhoI and hybridized with probe C. The germline and targeted alleles are indicated.
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3. Figure 2 Lack of Ossification in Cbfa1 Mutant Mice
Day 17.5 postcoitum wild type (a) and homozygous mutant (b) embryos were stained with Alcian blue/Alizarin red. Membranous and endochondral ossification are absent in Cbfa1−/− mice. Bone is stained red and cartilage blue.
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4. Figure 3 Skeletal Phenotype in Newborn Heterozygous Cbfa1 Mutant Mice
(a and b) Clavicle, scapula, and forelimb skeleton of +/+ (a) and +/− (b) mice. Note the clavicular rudiment and the missing deltoid tuberosity of the humerus in heterozygous animals.
(c and d) Neurocranium of Cbfa1+/+ (c) and Cbfa1+/− (d) mice. Sutures and fontanelles are widened in heterozygous mice. The parietal and interparietal bones are hypoplastic. Numerous small Wormian bones are present.
(e and f) Hyoid bone and sternum with ribs. Hypoplastic hyoid bone with delayed ossification in +/− mice (f) as compared to a wild-type littermate control (e). Wider xiphoid process of the sternum with two well-separated ossification centers in heterozygous mice (f).
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5. Figure 4
β-galactosidase Activity in Cbfa1 Heterozygous and Homozygous Embryos
(A) posterior view of 10.5 dpc −/− embryo showing staining in the prospective shoulder region (arrowhead). Bar = 450 μm.
(B–D) +/− embryos. (B) Lateral view of 11.5 dpc embryo showing staining in the maxillary (arrowhead) and mandibular processes of the first branchial arch, and in the scapula and developing humerus of the forelimb. Bar = 450 μm. (C) Lateral view of 12.5 dpc embryo showing staining in the limb bones and jaw. Bar = 2 mm. (D) Lateral view of a bisected 12.5 dpc embryo showing staining in the vertebral bodies, the ribs and skull. Bar = 1 mm.
(E) Dissected shoulder region from a 12.5 dpc −/− embryo. All developing bones are stained. Bar = 500 μm.
(F) Lateral view of a 12.5 dpc +/− embryo. The developing clavicle is marked by an arrowhead. Bar = 320 μm.
(G–J) −/− embryos. (G) Dissected pelvic region from a 12.5 dpc −/− embryo. The genital tubercle is marked by an arrowhead. Bar = 500 μm. (H) Transverse section through the radius and ulna showing staining in periosteal mesenchyme. Bar = 100 μm. (I) Section through a mammary gland showing staining in the epithelium. Bar = 100 μm. (J) Transverse section through the vertebral column showing staining in the notochord or nucleus pulposus. Bar = 100 μm.
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6. Figure 5 Disturbed Osteogenesis in Cbfa1 Mutant Mice
(a–c, e, and h) Endochondral and subperiosteal ossification in the tibia of newborn wild-type (a and e), heterozygous (b), and homozygous (c and h) Cbfa1 mutant mice. The growth-plate architecture is slightly less organized in heterozygous mice (b). Ossification centers, subperiosteal ossification, and formation of a marrow cavity are absent in homozygous mice (c). Higher magnification shows a periosteal osteoblast layer (arrowheads) and an active periosteal mesenchymal cell layer in wild-type mice (e). In Cbfa1−/− mice (h), the mesenchymal cell layer is small and inactive (arrowhead), and no osteoblasts are present (arrowhead). Some mineralization occurs within the cartilage (arrow).
(d and g). Clavicular development. Sections in the plane of the clavicle show endochondral ossification and cancellous bone containing hematopoietically active marrow in 19.5 dpc wild-type mice (d). In heterozygous mice, the medial end of the clavicle is cartilaginous but without any osteoblastic activity, while the remaining medial and lateral parts consist of cellular mesenchyme (g).
(f and i) Alkaline-phosphatase staining. Alkaline-phosphatase activity was easily detectable in 17.5 dpc wild-type long bones (f), with intense reactivity in the surface osteoblasts around the developing epiphyses (arrow), but was weak or absent in homozygotes (i).
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7. Figure 6 Cbfa1 Deletion in Ccd Mutant Mice
(a) RFLP analysis of the Cbfa1 gene in Ccd mutant mice. DNA from the offspring produced by intercrosses between M. castaneus and C57BL/10 mice heterozygous for Ccd, and from the parental strains, was analyzed. Southern blots containing DNA from cast/cast (A), cast/C57BL/10 (B), cast/Ccd (C), and C57BL/10 (D) mice digested with ApaI or TaqI are shown. An EcoRI–HindIII fragment of the mouse Cbfa1 cDNA representing the 3′ portion of the translated sequence was used as probe. The castaneus allele is indicated by open arrowheads, the C57BL/10 allele by closed arrowheads. Note the absence of the C57BL/10 Cbfa1 allele in the Ccd mice.
(b) Genomic organization of the Ccd locus as determined by allelic differences between strains. The deleted markers and genes are printed in italics.
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